To prevent the rolling of a standing automobile on a level surface it is usually necessary to engage the brakes. From a technical standpoint there are a large number of procedures, which could prevent the unintentional rolling of a standing automobile. Braking power is usually applied by way of a control unit on the controllable actuator of the brakes. If the vehicle is moved, then the automatic braking is released. If shutting off the engine is not enough, along with applying the clutch and transmission to the wheels to prevent the inadvertent rolling of the vehicle on an inclined surface, then this is a dangerous situation. If the brakes are released too late, this causes needless torque on the vehicle brakes and can lead to increased wear and tear, increased fuel consumption and unnecessary emission of pollutants.
From DE 102 44 024 A1, a procedure is known which prevents the unintentional rolling of a standing vehicle which, with an activated stop function against inadvertent rolling, can be used to apply the brakes through operation of the clutch regulating distance either manually or automatically when the clutch is released. The clutch regulating distance, which is used when the brakes are released, is calculated with the help of ascertained values of the vehicle weight and the grade of the roadway.
In vehicles with the automatic operation of the start-up clutch, the operating position of the clutch at start-up along with the rate of motion of the accelerator pedal are automatically determined. Because drivers depress the accelerator quickly or slowly and the accelerator pedal over time because of more or less resistance, it follows that the control systems would have to calculate the time differently at which the clutch regulating distance is set. The release of the brakes, along with the determination of the preset clutch, regulating distance occurs after a signal is issued to the brakes with a specific time delay. Then this procedure can transfer the drive motor at the time of the release of the brakes according to the moving speed and scan angle of the accelerator pedal to the wheels. It is possible that the vehicle can experience unintentional rolling or also an unintentionally fast acceleration when the brakes are released due to too light or heavy torque on the wheels.
With other control systems for automated transmissions and automatically controlled clutches, the drive motor is limited to a certain engine momentum or speed. Different accelerator pedal positions will be dependant then firstly on the engaging speed of the clutch and/or the speed of momentum and the vehicle's achieving the desired speed.
From DE 101 05 749 A1, a procedure is known to aid a utility vehicle at low speed, which is dependent on the position of the accelerator pedal and the depression of the vehicle friction brakes and the clutch, at the same time, and on each coordinating with one another. Under working conditions and the increased angle of the accelerator pedal, the brake pressure is decreased and, at the same time, the clutch pedal is depressed. The relationship between the accelerator pedal, the brake pressure and the clutch pedal is determined by the weight of the loaded vehicle.
The switch operation is a special driving mode used by drivers of utility vehicles and is not being compared to the starting-up operation. The switch mode depends on an exact positioning of the vehicle and it is accepted that the drive motor with the clutch works against the brake operation. Under operating conditions, the switch helper can work, given any position of the vehicle, not just one position. Starting-up help is restricted to the shortest possible period of time or to the lowest power of the engine on the brakes.
From DE 44 21 088 C2, a starting-up servo-mechanism is known for driving with automatic gears in which the control unit with low speed works with the brake system. When the accelerator pedal is at position zero, the control unit activates the brake system. If any of these conditions changes, it deactivates the brake system. When a vehicle has stopped on an incline, the starting-up servo-mechanism is activated but, when the brake pedal is released and the accelerator pedal depressed, the starting-up servo-mechanism is disengaged.
This procedure does not prevent the inadvertent rolling of the vehicle; it just provides a short-term solution until the brakes are released which makes it the responsibility of the driver to depress the brake pedal or accelerator pedal. If no sufficient torque is provided by the engine by the end of the short time span to hold the vehicle in its previous position or if the clutch is not released in time, the vehicle will inadvertently roll in the direction of the incline. This can be a dangerous situation if the driver is in the mountains and, when he releases the accelerator pedal, the brakes engage. In this case, the driver would instinctively depress the accelerator further and/or he would release the brake pedal or disengage the brake system and the brake system would automatically disengage when the higher speed is achieved.
Additionally, it is known from DE 198 48 448 A1 that brake pressure control can be activated when the vehicle is standing and after the driver turns on the operating system and selects the mode “starting-up assistant”. The vehicle brakes for a short time can be applied with brake pressure. The driver can select a starting-up setting under which the clutch is engaged, but the brake pedal and accelerator pedal will not operate. In this case, the clutch would be in control. As soon as the clutch is switched to a higher gear, the starting-up assistant is engaged and the brake is released.
In DE 198 48 448 A1, the described brake assistant would receive a signal from the accelerator pedal to start-up and would use a selected setting. The course of the starting-up process and, in particular, the timing of the disengagement of the brake is not independent of the position of the accelerator pedal or from the engine load which have an influence on the clutch setting which determines when the brake gets released. If the driver depresses the accelerator pedal way down, the engine picks up speed, but the engine load is determined not by the position of the accelerator pedal, but by the position of the clutch. Once the engine load is determined and the clutch is set, a signal is sent to the release the brakes.
The moving speed and angle of the accelerator pedal is not evaluated in this instance. That is because a certain response time is needed to take the brakes off the wheels after giving the order to release the brakes. This response time cannot be predicted. It depends on the speed of the vehicle, the engine strength and the wheels. When the accelerator pedal is depressed quickly and heavily, the engine power rises in the period between the signal to release the brakes and the actual release of the brakes, which doesn't happen when the pedal is depressed slowly and lightly. Also this procedure does not allow optimum time between when the order is given to release the brakes and when it is carried out.
For example with pneumatic actuators, the target default for the adjustment speed of the clutch deviates somewhat. In addition with the driving motor, a number of revolutions or a torque default with the expected dynamics and/or a quality converted into actual values cannot be assumed. So, for example, more highly prioritized control interferences could be placed into the motor control of a vehicle (to operate through the brake system) to allow for a deviation from the requirements of a starting situation.
With this background for the invention, the task is the basis to present a control procedure for a starting assistant for a vehicle with a transmission and an automatically operable transmission clutch with which the time for the expenditure of the instruction is coordinated with the release of the brake better so that the time the actual instruction is carried out is aligned to the engine torque.